Conveyor system and installation for blow-moulding of containers

ABSTRACT

A conveyor system for discrete entities, including a gathering member supplied by at least two upstream units ( 26, 27 ) each of which brings to the gathering member a series of entities ( 11, 13 ), and wherein the entities leave the gathering member in a single line. The gathering member includes a gathering wheel ( 36 ) driven in rotation and provided with several slots ( 38, 39 ) emerging radially at the periphery of the wheel for receiving each entity, and the slots of a common series have the same radial depth, the series of slots being differentiated by the depth of their slots, and each series of slots is associated exclusively with an upstream unit.

The invention concerns conveyor systems for discrete entities, that is,for carrying individual items.

The invention will be more particularly described within the scope ofits application to a container blow-molding facility in which thecontainer is obtained by blowing a preform previously produced byinjection.

However, the invention will find application in any conveyor system inwhich it is desired to merge in a single line and at a specific rateentities coming from several “sources.”

Such a merging would be necessary, for example, in a facility whenseveral slow-speed machines are used to perform the same step, inparallel, the entities being then all processed in a second step by ahigh-speed machine.

The example that will be described in detail is that of the feed for apreform temperature condition oven. Such an oven generally has aconveyor chain or wheel that transports the preforms in front ofinfrared lamps in order to bring them to a temperature at which thethermoplastic material becomes deformable for the last blow-moldingoperation.

The oven is usually fed with preforms by a single feed unit. This feedunit usually has a bin in which the preforms are stored in bulk, aninclined belt conveyor, a device to disentangle the preforms, and aninclined feed rail at the bottom of which the vertically orientedpreforms are accumulated to form a buffer stock. At the bottom of thisrail, an automatic gate allows a preform to pass at regular intervals,the preform then being engaged by a wheel with recesses.

Such feed units have the disadvantage of a lack of reliability at highspeed, particularly because of the disentangling operation, which isvery delicate.

Also, for the proper operation of the blow-molding facility, it isproposed here to feed the facility by two feed units that work inparallel. Each feed unit thus only has to provide half of the rate ofthe blow-molding facility.

However, it then becomes necessary to provide a conveyor system thatmerges the preforms furnished by the two feed units in such a way thatat the oven, everything takes place as though the facility had a singlefeed unit.

This system should be simple, reliable and small in size.

The invention therefore proposes a system for conveying discreteentities, which system has a merging device fed by at least two upstreamunits each of which leads to the device for merging the entities thatare spaced according to a first rate of speed, and of the type in whichthe entities leave the merging device in a single line at a second rateof speed, characterized in that the merging device has a merging wheelthat is driven in rotation and is provided with several series ofrecesses that open radially toward to periphery of the wheel, in thatthe entities are each radially engaged from the exterior toward theinterior in one recess, in that the recesses of a same series have thesame radial depth, the series of recesses being differentiated by thedepth of their recesses, in that each series of recesses is associatedexclusively with one upstream unit.

According to other characteristics of the invention:

the different series of recesses fit into each other;

each upstream unit delivers its entities at a different loading pointthat occupies an angularly fixed position around the axis of the mergewheel, and the point of loading associated with the series of deepestrecesses is placed the farthest upstream on the trajectory of therecesses of the merge wheel;

after the point of loading, the entity is guided between two internaland external slide rails that are placed in a plane axially offset withrespect to the plane of the merge wheel, and the external slide railforces the entity toward the bottom of the recess;

the difference in depth between two recesses of two different series isgreater than the dimension of one entity in the radial direction;

the merging device has a slide rail which, on one part of the path ofthe wheel between the point of loading of the last series of entitiesand the point of discharge, cooperates with the entities to push themtoward the peripheral edge of the merge wheel;

at least one of the upstream units has a wheel with recesses that isplaced tangentially to the merge wheel; and

the entities are preforms for the blow-molding manufacture of containersfrom thermoplastic material.

The invention also proposes a facility for blow-molding containers frompreviously injected preforms, of the type having an oven for temperatureconditioning the preforms, characterized in that the oven is fed withpreforms by at least two feed units that are arranged in parallel andeach of which delivers a series of regularly spaced preforms, and inthat, between the feed units and the oven, the preforms are transportedby a conveyor system incorporating any one of the precedingcharacteristics, the system merging the series of preforms in order toform a single series of preforms.

Other characteristics and advantages of the invention will appear in thefollowing detailed description as well as in the attached drawings inwhich:

FIG. 1 is a diagrammatic view illustrating a facility for blow-moldingcontainers in which the oven is fed with preforms by two units operatingin parallel; and

FIG. 2 is a diagrammatic representation of a conveyor system accordingto the invention.

FIG. 1 illustrates a machine 10 for blow-molding containers fromthermoplastic material, for example polyethylene terephtalate (PET)bottles. The machine 10 essentially has a blow-molding unit 12 and atemperature condition oven 14 in which the preforms 11, 13, producedpreviously by injecting molding, are brought to a temperature that ishigher than the glass transition temperature of the material of whichthey are made. In an original way, the oven 14 is fed by two feed units16, 17 arranged in parallel. The units 16, 17 can be standard commercialparts.

For example, these units 16, 17 can be of the type having a bin 18 inthe form of a hopper, a conveyor belt 20, a device 22 for untangling thepreforms and an inclined feed rail 24. The preforms are removed from thebin 18, vertically oriented by the untangling device 22, and accumulateat the bottom of the rail 24 simply by gravity. They are then held, forexample, by a ring placed at the base of their neck. At the bottom ofthe rail, a gate (not shown), for example made in the form of aretractable arm, allows the preforms to pass one by one so that they areengaged by a feed wheel 26, 27. The feed wheel here comprises a wheelwith recesses. Each feed unit 16, 17, furnished with its feed wheel 26,27, is able to furnish a series of preforms spaced according to a firstrate of speed. Feed units of this type are used, for example, in theblow-molding facilities marketed by the applicant.

Illustrated in FIG. 2 are two feed wheels 26, 27, from the two units 16,17, as well as the lower end of the two associated feed rails 24 bywhich the two series 11, 13 of preforms arrive.

In a known way, the feed wheels 26, 27 are each composed of a disk 28which has around its periphery recesses 30 that are appreciablysemicircular and regularly spaced. The disks 28 are driven continuouslyin rotation around their respective axes A1 and A2. The gate (notrepresented) of the feed system is controlled so that when a recess 30faces the end of the rail 24, a preform is released, is engaged in therecess, which then drives it in rotation. An external circular guide 32,31 prevents the preform from escaping from the recess 30, the radialdepth of which is appreciably equal to half the diameter of the preform.After they are taken by the feed wheels, the preforms are alwaysconveyed individually, the transfer always being performed without thepreform being released. Indeed, it is important that the preformpreserve its orientation, particularly in order to be able to becontrolled in the oven.

According to the methods of the invention, the two feed wheels 26, 27,which are identical, are intended to feed the same merge wheel 36. Atthe outlet of this merge wheel the two series 11, 13 of preformsprovided by the feed units are merged into a single set of preforms at anew spacing, preferably the spacing of the preform conveyor system inthe oven 14.

The merge wheel 36 also comprises a disk that is driven in rotationaround its axis A3 in synchronization with the two feed wheels 26, 27.According to the invention, the merge wheel has recesses that are madein the periphery of the disk and are distributed in as many series asthere are feed units. The series of recesses differ by the radial depthof their recesses, which are oriented radially with respect to the axisA3 and are open outward.

In the example illustrated, the merge wheel 36 has two series ofrecesses 38, 40. The recesses 38 of the first series have a relativelylarge radial depth, for example on the order of twice the diameter ofthe preforms. The recesses 40 of the second series are also semicircularand have a depth on the order of one half the diameter of the preform.

The recesses of both series are interspersed along the periphery of thedisk in such a way that there is alternatively a recess of one of theseries then a recess of the other series. The recesses 38, 40 of themerge wheel are spaced circumferentially at a rate of one half the spaceseparating two recesses 30 of the feed wheels 26, 27.

The two feed wheels 26, 27 are arranged tangentially to the merge wheel36 and are synchronized therewith so that when a recess 30 is at thepoint of tangency, it is exactly in front of a recess 38, 40 of themerge wheel. According to the invention, the recesses 30 of a given feedwheel will necessarily be in front of a recess of a given series of themerge wheel 36. Conversely, the two points of tangency of the mergewheel 36 are chosen so that the recesses 38, 40 of a same series canonly face the recesses of one of the two feed wheels. The loading of thepreforms in the recesses of the merge wheel is accomplished radiallyfrom the outside toward the inside. Even at the moment it passes fromthe feed wheel to the merge wheel, the preform continues to perfectlyheld and indexed, which makes it possible to preserve exactly thespacing between two preforms of the same series.

The guidance system according to the invention, therefore, comprisesslide rails that make it possible to determine the radial position ofthe preforms that are taken in the recesses of the merge wheel. Theseslide rails, for example, are made in the form of fixed plates that arearranged in a plane axially offset with respect to the plane of thedisks of the wheels, and one edge of which forms a slide rail on whichthe preforms are radially supported and slide when they are driven inrotation by the wheels.

In FIG. 2 it can be seen that the first feed wheel 26, the point oftangency of which is the farthest away from the point of tangency of themerge wheel 36 with a discharge wheel 42, is intended guide the preforms11 into the deep recesses 38 of the merge wheel. The loading of thepreforms 11 of this first series is therefore done at this point oftangency, due to an internal slide rail 44 and to a first external sliderail 46. The external slide rail 46 pushes the preforms out of therecesses 30 of the first loading wheel 26. The two slide rails 44, 46then cooperate with the preforms of this first series to push themradially into and toward the bottom of the recesses 38 as they progressangularly around the axis A3.

It can be seen that, by the action of the slides 44, 46, the preforms 11of this first series have reached the bottom of the respective recess 38before they angularly reach the point of tangency of the second feedwheel 27 with the merge wheel 36.

In the example illustrated, the exterior slide rail 46 corresponding tothe first feed wheel 26 and the guide 34 of the second feed wheel 27 areformed by two edges of the same plate element that thus has a sharppoint 48 delimited by the respective ends of the guide 34 and of thefirst exterior slide rail 46. The end of this point 48 is situatedangularly just before the point of loading of the second series ofpreforms, this point corresponding to the point of tangency of thesecond feed wheel 27 with the merge wheel 36. This point 48 extendsradially with respect to the axis A3 between the bottom of the recesses38 of the first series and that of the recesses 40 of the second series.Obviously the point 48 should not create an obstacle to a preform 11 ofthe first series that would be guided by a recess 38 of the merge wheel36.

As a result of the invention, it can be seen that the first preforms 11are thus radially released toward the interior so as not to interferewith the guide 34 of the second feed wheel 27.

A second exterior slide rail 50 extends along an arc of a circle aroundthe axis A3 between the point of loading of the preforms 13 of thesecond series and the point of discharge of all the preforms thatcorresponds to the point of tangency of the merge wheel 36 with thedischarge wheel 42. The principal purpose of this second slide rail 50is to hold the preforms of the second series supported at the bottom oftheir recesses 40, without which these preforms would not stay on thewheel 36.

Unlike the first exterior slide rail 46, the interior slide rail 44extends along a second section between the point of loading of thesecond series of preforms 13 and the point of discharge. The contour ofthis second section is such that it forces the preforms 11 of the firstseries radially toward the exterior once they have passed the dischargepoint of the preforms of the second series. Beyond this point, there isno longer any risk of the preforms 11 of the first series interferingwith a guide of the second feed wheel. The second section of theinterior slide rail thus makes it possible radially to place thepreforms 11 from the first series on the same radius as the preforms 13from the second series.

Thus, at the point of discharge, the preforms 11, 13 from both seriesare taken radially between the interior slide rail 44 and the secondexterior slide rail 50. They can then be taken over by the dischargewheel 42.

The merge device thus proposed is therefore completely reliable becausethe entities it transports, for example the preforms, remain perfectlyindexed at all times during their course because they are held in therecesses. There is therefore no risk of their becoming snarled orblocked against part of this component, as can occur with a switchingmechanism. Of course, they also preserve their vertical orientation forthe full length of their path on the feed and merge wheels.

The invention has just been described for a case in which the precedingunit has wheels with recesses that provide the feed. However, a mergewheel according to the invention could also be used without a feedsystem or by using a different system. The entities could thus be placedon the merge wheel by synchronized transfer arms.

What is claimed is:
 1. System for conveying discrete entities, whichsystem has a merging device (36) fed by at least two upstream units (16,17) each of which leads to the device for merging the entities (11, 13),and of the type in which the entities leave the merging device (36) in asingle line, characterized in that the merging device has a mergingwheel (36) that is driven in rotation and is provided with severalseries of recesses (38, 40) that open radially toward to periphery ofthe wheel, in that the entities are each radially engaged from theexterior toward the interior in one recess, in that the recesses of asame series have the same radial depth, the series of recesses beingdifferentiated by the depth of their recesses, and in that each seriesof recesses is associated exclusively with one upstream unit. 2.Conveyor system according to claim 1, characterized in that thedifferent series of recesses (38, 40) fit into each other.
 3. Conveyorsystem according to claim 1, characterized in that each upstream unit(16, 17) delivers its entities at a different loading point thatoccupies an angularly fixed position around the axis (A3) of the mergewheel (36), and in that the point of loading associated with the seriesof deepest recesses (38) is placed the farthest upstream on thetrajectory of the recesses of the merge wheel (36).
 4. Conveyor systemaccording to claim 3, characterized in that after the point of loading,the entity is guided between two internal (44) and external (46) sliderails that are placed in a plane axially offset with respect to theplane of the merge wheel (36), and in that the external slide rail (46)forces the entity toward the bottom of the recess (38).
 5. Conveyorsystem according to claim 1, characterized in that the difference indepth between two recesses (38, 40) of two different series is greaterthan the dimension of one entity in the radial direction.
 6. Conveyorsystem according to claim 1, characterized in that the merging devicehas a slide rail (44) which, on one part of the path of the wheelbetween the point of loading of the last series of entities and thepoint of discharge, cooperates with the entities to push them toward theperipheral edge of the merge wheel (36).
 7. Conveyor system according toclaim 1, characterized in that at least one of the upstream units has awheel (26, 27) with recesses that is placed tangentially to the mergewheel (36).
 8. Conveyor system according to claim 1, characterized inthat the entities are preforms for a blow-molding manufacture ofcontainers from thermoplastic material.
 9. Facility for blow-moldingcontainers from previously injected preforms, of the type having an oven(14) for temperature conditioning the preforms, characterized in thatthe oven (14) is fed with preforms by at least two feed units that arearranged in parallel and each of which delivers a series of regularlyspaced preforms, and in that, between the feed units and the oven, thepreforms are transported by a conveyor system according to any of thepreceding claims, the system merging the series of preforms in order toform a single series of preforms.